title: The effect of photopolymerization on stem cells embedded in hydrogels.
abstract: Photopolymerizable hydrogels, formed by UV-exposure of photosensitive polymers in the presence of photoinitiators, are widely used materials in tissue engineering research employed for cellular entrapment and patterning. During photopolymerization, the entrapped cells are directly exposed to polymer and photoinitiator molecules. To develop strategies that prevent potential photoexposure-damage to osteoprogenitor cells, it is important to further characterize the effects of photopolymerization on the exposed cells. In this study we analyzed the viability, proliferation and osteogenic differentiation of multipotent stromal cell (MSC) monolayers after exposure to UV-light in the presence of Irgacure 2959, a frequently used photoinitiator in tissue engineering research. Cell cycle progression, apoptosis and osteogenic differentiation of encapsulated goat MSCs were studied in photopolymerized methacrylate-derivatized hyaluronic acid hydrogel and methacrylated hyperbranched polyglycerol gel. We demonstrate adverse effects of photopolymerization on viability, proliferation and reentry into the cell cycle of the exposed cells in monolayers, whereas the MSCs retain the ability to differentiate towards the osteogenic lineage. We further show that upon encapsulation in photopolymerizable hydrogels the viability of the embedded cells is unaffected by the photopolymerization conditions, while osteogenic differentiation depends on the type of hydrogel used.
authors.affiliation: Department of Orthopaedics, University Medical Center Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: Natalja E
authors.initials: NE
authors.lastname: Fedorovich
authors.forename: Marion H
authors.initials: MH
authors.lastname: Oudshoorn
authors.forename: Daphne
authors.initials: D
authors.lastname: van Geemen
authors.forename: Wim E
authors.initials: WE
authors.lastname: Hennink
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Alblas
authors.forename: Wouter J A
authors.initials: WJ
authors.lastname: Dhert
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D053148:Caspase 3 / Q000378:metabolism; D002452:Cell Count; D002453:Cell Cycle / Q000528:radiation effects; D002454:Cell Differentiation / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D016922:Cellular Senescence / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D004249:DNA Damage; D006041:Goats; D006820:Hyaluronic Acid / Q000737:chemistry; D020100:Hydrogels / Q000378:metabolism*; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D010012:Osteogenesis / Q000528:radiation effects; D011108:Polymers / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000201:enzymology / Q000378:metabolism* / Q000528:radiation effects*; D014466:Ultraviolet Rays; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D020100:Hydrogels; D047908:Intracellular Signaling Peptides and Proteins; D011108:Polymers; D006820:Hyaluronic Acid; D000469:Alkaline Phosphatase; D001616:beta-Galactosidase; D053148:Caspase 3